Chemical compositions and methods



Patented Oct. 13, 1953 CHEMICAL COMPOSITIONS AND METHODS Charles W.Todd, Wilmington, Del., as'signor to E. I. du Pont de Nemours & Company,Wilmington, Del., a corporation of Delaware No Drawing. ApplicationFebruary 14, 1952, Serial No. 271,633

3 Claims.

This invention relates to methods for killing weeds, or undesirableplant growth, and to compositions employed in practicing such methods.

This application is a continuation-impart of my copending applications:Serial No. 131,498 filed December 6, 1949, Serial No. 186,118 filedSeptember 21, 1950, Serial No. 231,061 filed June 11, 1951, and SerialNo. 231,062 filed June 11, 1951 all or which are now abandoned exceptapplication Serial No. 186,118.

The herbicidally active compounds of the invention are substituted ureasrepresented by the Iormula:

'0 R (1) l g A-N- N where R is an alkyl radical having up to two carbonatoms and R" is an alkyl radical up to four carbon atoms when R ismethyl and up to two carbon atoms when R is ethyl, and A is anortho-substituted phenyl group selected from Q C? .Q

where X is halogen, n is a positive integer up to 2, and R is alkylhaving up to four carbon atoms, the ortho-substituted phenyl grouphaving one hydrogen on one of the nuclear carbons ortho to the group--NHCON (R')R".

It will be seen that the herbicidally active compounds of the inventionare especially characterized by having a single substituent ortho to the-NHCON (R)R" group. In other words, they are mono-ortho substituted.Further, the only substituents on the phenyl ring are either lower alkylor halogen. An additional class characteristic of the compound is thatthey are all tri-substituted ureas, the aromatic group being the onlysubstituent of the urea nitrogen atom to which it is bonded.

R, R and R" in the above Formula 1 and in the description following thatformula are preierably methyl and X is preferably chlorine.

The herbicidally active compounds of the invention are prepared by thereaction of an ap propriate ortho substituted phenyl isocyanate with adialkyl amine, The following equation 2 showing specific reactantsillustrates the reaction:

QNCO enema -r H O CH 3 i N- N\ c1 sary to supply heat. Thus the reactionis conveniently carried out by first mixing the isocyanate with theinert solvent at room temperature and then gradually adding thesecondary amine reactant while permitting the temperature to increasethru the range of say 25 to C. The tri-substituted urea products aregenerally quite insoluble in the solvent used and, therefore,precipitate out as formed and are readily separated from the reactionmass.

The ortho substituted phenyl dialkyl ureas oi the invention are. for themost part, white crystalline solids. They are insoluble or only slightlysoluble in water and cold benzene and, in general, appreciably solublein dioxane. acetone, ethylacetate, ethanol, andhot benzene.

The ortho substituted phenyl isocyanates used as starting materials canbe prepared by the general method described in the literature (Vittenet,Bull, Soc. Chim. (3) 21, 586, 954 (1899 Organic Synthesis, Collective,vol. II, page 453; and U. S. Patent 2,428,843) which consists in heatingthe haloaryl carbamyl chloride first obtained by treating the haloarylprimary amine with phosgene at ordinary temperature in the presence ofan appropriate solvent or reaction media.

Illustrative of the herbicidally active compounds of the inventionrepresented by Formula 1 above are:

3 (o chlorophenyl) 1,1 diethylurea 3 (o chlorophenyl) 1,1 dimethylurea 3(o chlorophenyl) 1 methyl 1 isopropylurea 3 (o chlorophenyl 1 methyl 1 npropylurea 3 (2,4,5, trichlorophenyl) 1 methyl 1 isobutylurea 3 3 (2methyl 4 chlorophenyl) 1,1 dimethylurea i 3 (2 methyl chlorophenyl) 1,1dimethylurea 3 (2 methyl 3,5 dichlorophenyl) 1,1-

dimethylurea 3 (o chlorophenyl) 1 methyl 1 ethylurea 3 (2 chloro ptolyl) 1 methyl 1 isopropylurea 3 (2 chloro p tolyl) 1 methyl 1 sec.

butylurea 3 (2 chloro 4 ethylphenyl) 1,1 di

methylurea 3 (2,3,5, trichlorophenyl) 1,1 dimethylurea 3 (2,4,5,trichlorophenyl) 1 methyl 1 ethylurea 3 (2,4,5, trichlorophenyl) 1methyl 1 isopropylurea 3 (o chlorophenyl) 1 methyl 1 sec.

butylurea 3 (o chlo'rophenyl) 1 methyl 1 isobutylurea 3 (o chlorophenyl)1 methyl 1 tert.

butylurea 3 (o chlorophenyl) 1 methyl 1 n butylurea 3 (2 methyl 4chloro) 1 methyl 1 sec.

butylurea 3 (2 ethyl 4 chlorophenyl) 1,1 dimethylurea 3 (2 sec. butyl 4chlorophenyl) 1,1 dimethylurea 3 (2 chloro 4 sec. butylphenyl) 1,1diethylurea 3 (2 bromo p tolyl) 1',1 dimethylurea 3 (2,4 dichloro 5fluorophenyl) 1,1 dimethylurea 3 (2,4,5, trichlorophenyl) 1,1dimethylurea 3 (o-bromophenyl) 1,1 dimethylurea 3 (2 chloro p tolyl) 1,1dimethylurea 3 (2 chloro p tolyl) 1 methyl 1 ethylurea 3 (2 methyl 4,5dichlorophenyl) 1,1

dimethylurea 3 (2 methyl 4 chlorophenyl) 1 methyll-ethylurea 3 (2 methyl4 chlorophenyl) 1 methyl- 1 n propylurea For application of theherbicidally active compounds of the invention, the compounds arepreferably admixed with a carrier material or conditioning agent of thekind used and referred to in the art as a pest control adjuvant ormodifier in order to provide formulations adapted for ready andefiicient application to weeds or unwanted plants using conventionalapplicator equipment.

Thus, one or more of the herbicidally active compounds of the inventionare admixed with carrier or adjuvant materials to provide formulationsin liquid or solid form. For example, solutions of the compounds of theinvention in organic solvents, such as cyclohexanol, furfural,

- solvent carrier.

acetone, isobutanol, ethanol, isopropylacetate,

and the like can be applied directly as herbicides. More economical andpractical formulations are prepared by admixing or dispersing theherbicidally active compounds with a non-solvent carrier which may beeither solid or liquid. Thus, herbicidal dust compositions arecompounded to give homogeneous free-flowing dust by admixing the activecompounds with finely divided solids, preferably, talcs, natural clays,pyrophyllite, diatomaceous earth, and flours such as walnut shell,wheat, redwoo 8 been and cottonseed flours. Other inert solid carrierswhich can be used to prepare the herbicidal formulations includemagnesium and calcium carbonates, calcium phosphate, sulfur, lime, etc.either in powder or granular form. The percentage by weight of theessential active ingredients will vary according to the manner in whichthe composition is to be applied but, in general, will be 0.5 to byweight of the herbicidal composition.

Liquid herbicidal compositions can contain, for example, one of theactive herbicidal compounds of the invention dispersed in water or othernon- To secure such homogeneous dispersions, a surface-active agent isused. In fact, the preferred herbicidal compositions of this inventionwhether in liquid or in solid form contain the herbicidally activecompound homogeneously admixed with a surface-active agent sometimesreferred to in the art as wetting, dispersing or penetrating agents.These agents, which will be referred to hereinafter more simply assurface-active dispersing agents, cause the compositions to be easilydispersed in water to give aqueous sprays which, for the most part,constitute a desirable method of application.

The surface-active dispersing agents employed can be of the anionic,cationic or nonionic type and include, for example, sodium and potassiumoleates, the amine salts of oleic acid such as morpholine anddimethylamine oleates, the sulfonated animal and vegetable oils such assulfonated fish and castor oils, sulfonated petroleum oils, sulfonatedacyclic hydrocarbons, sodium salt of lignin sulfonic acid (goulac)alkylnaphthalene sodium sulfonate, sodium salts of sulfonatedcondensation products of naphthalene and formaldehyde, sodium laurylsulfate, disodium monolauryl phosphate, sorbitol laurate,pentaerythritol monostearate, glycerol monostearate, diglycol oleate,polyethylene oxides, ethylene oxide condensation products with stearylalcohol and octylphenol, polyvinyl alcohols, salts, such as the acetateof polyamines from reductive amination of ethylene/carbon monoxidepolymers, laurylamine hydrochloride, laurylpyridinium bromide,stearyltrimethylammonium bromide, cetyldimethylbenzyl ammonium chloride,lauryldimethylamine oxide, and the like. Generally, the surface-activeagent will not comprise more than about 5 to 15% by weight of thecomposition, and in certain compositions the percentage will be 1% orless. Usually the minimum lower concentration will be 0.1%.

The herbicidal compositions of the invention can also have incorporatedtherein oils, fats or similar vehicles such as cottonseed oil, oliveoil, lard, paraffin oil, hydrogenated vegetable oils, etc. Adhesivessuch as gelatin, blood albumin, resins, for example, rosin, alkyd resinsand the like, can also be used in certain compositions to increaseretention or tenacity of deposits following application.

Water-dispersible liquid compositions can be prepared by incorporatingwith the ureas and surface-active dispersing agents various organicliquids such as furfural, methanol, isopropanol, isobutanol, xylol,cresol, cyclohexanone, acetone, methyl ethyl ketone, kerosene,trichloroethylene, dimethylformamide, dimethylacetamide, alkylatednaphthalenes, and the like. Such compositions are readily dispersible inwater and provide excellent aqueous herbicidal sprays for fieldapplications. The proportion of surface-active dispersing agent to ureacan be 0.1 to by Alternatively, the dry powdered compositions can bedusted directly on the plants. I

The active ingredients are, of course, applied in amount sufficient toexert the desired herbicidal action. The amount of herbicidally activecompounds present in the compositions as actually applied for destroyingweeds will vary with the herbicidal activity of the active ingredients,the purpose for which the application is being made, the manner ofapplication, the particular weeds for which control is sought, and likevariables. Certain of the specific examples to follow will illustratevarious kinds and amounts of application and the results obtainedthereby. In general, the herbicidal compositions as applied in the formof a spray or a dust will contain from about 0.02% to 95% by weight ofherbicidally active ingredient.

The class of herbicidally active compounds of this invention hascharacteristics which make the compounds especially valuable for certainherbicidal uses. They are useful in destroying weeds in growing rowcrops by treatment of the weeds between the rows. They are particularlyuseful as contact herbicides for the control of annual weeds.

i The solid and liquid compositions described and employed herein forapplication of the essential active herbicidal ingredient all have thecommon property of permitting application of the herbicidal compositionsthrough suitable jets, nozzles, or spreaders adapted to the handling ofgranular materials onto the plants being treated and will, forconvenience, be designated as fluent carriers. The fluent carriers withwhich this invention is primarily concerned are non-solvent fluentcarriers.

In order that the invention may be better understood, the followingexamples are given in addition to the examples already given above. Theexamples illustrate typical compounds of the invention, methods fortheir preparation. herbicidal formulations employing such compounds,herbicidal applications, and the results obtained.

EXAMPLE 1 3- (o-chlorophenyl) -1,1-diethylurca o-Chlorophenyl isocyanate(30.6 parts) was added dropwise to a solution of 16 parts ofdiethylamine and 258 parts of dry dioxane with stirring. Heat wasliberated on contact of the reactants and the temperature was maintainedat 25-35 C. On pouring the reaction mixture into 500 parts of water, alight-colored oil separated. This oil was extracted with diethyl ether,and the ether extract was then dried over anhydrous magnesium sulfate.Distillation yielded a fraction (37 parts) of3-(ochlorophenyl)-l,ldiethylurea boiling at 137-l39 C./0.5 mm.

Anal. calcd. for C11H15ClN2O: C, 58,35; H, 6.67. Found: C, 58.19; H,6.86.

3- (2,4,5-trichlorophenyl) 1,1 -dimethulurea A solution of 16 parts byweight of 2,4,5-trichloroaniline in 75 parts by weight of anisole wastreated with 10 parts by weight of phosgene and heated until theresulting mixture was a clear solution. The solution was cooled to 25 C.and 4.3 parts by weight of dimethylamine was added with stirring. Themixture was then heated at the reflux temperature for 15 minutes. Oncooling 12 parts by weight of 3-(2,4,5-trichlorophenyl)-l,1-dimethylureaseparated as a white crystalline product; M. P. 111-2 0., yield 55%.

Anal. calcd. for CnHcClaNzO: 01,3933. Found: Cl, 39.13. 39. 42.

EXAMPLE 3 3-(o-chl0rophenyl) -1,1 dimethylurea Dimethylamine was passedinto a solution of 46.1 parts by weight of o-chlorophenyl isocyanate in110 parts by weight of absolute ether until present in excess. Thereaction mixture was heated to reflux for 10 minutes, cooled, and whitecrystalline 3-(o-chlorophenyl) -l,1 dimethylurea precipitated and wasseparated and dried in a vacuum oven at 50 C. over phosphoric anhydride.The yield was 53.1 parts by weight (89%) M. P. 94.1-5.4 C.

Anal. calcclfor CaHrlClNzO: Cl, 17.87. Found: Cl, 17.90, 17.95.

Additional herbicidal reactive compounds of the invention such as thosetabulated previously are similarly prepared according to the methodsdescribed in the foregoing detailed examples.

EXAMPLE 4 Dust formulations The following compositions are adapted fordirect application as dusts for the destruction of weeds usingconventional dusting equipment. The dusts are made by blending or mixingthe ingredients and grinding the mix to give compositions having anaverage particle size less than about 50 microns.

3- (2-znethyl-4-chlorophenyl) -1-methyll-isopropylurea 20 Talc3-(2-chloro-4-sec. butylphenyl) 1,

l-dimethylurea 5 Cottonseed oil 4 Walnut shell flour 91 100 EXAMPLE 5Water-dispersible powders The following powdered compositions areadapted for dispersing in water for application as a spray for thedestruction of weeds. The powdered compositions are made by intimatelymixing the listed ingredients using conventional mixing or blendingequipment and then grinding the mixture to give a powder having anaverage particle size less than about 50 microns.

3-(o-chlorophenyl)-1,l-dimethylurea '15 Fullers ear 23.75 Sodium laurylsulfate, 50% (wetting agent) 1 1 Methyl cellulose, 15 cps. (dispersingagent) 0.25

3-(2,4,5-trichlorophenyl) -1,1- dimethylurea 80 Sodium disulfonate ofdibutyl phenylphenol (wetting and dispersing agent) Bentonite 18 100EXAMPLE 6 Oil-water dispersible powders The following powderedcompositions are adapted for use in the preparation of spraycompositions using either an oil, water, or a combination of oil andwater as the liquid diluent. The powders are made by mixing and grindingas in the case of the powders of Example 4.

EXAMPLE 7 Water-dispersible liquid Compositions The followingcompositions are in a liquid form and are adapted for addition to waterto give aqueous dispersions for application as sprays. The ureaherbicides are generally quite insoluble in most oils. Therefore, theliquid compositions ordinarily are not complete solutions but rather aredispersions of solid in an oil. The liquid or fluid compositions shownare prepared by thoroughly mixing and dispersing the active compoundsand conditioning agent or agents in an organic liquid diluent.

S-(o-chlorophenyl) 1 methyl-1-sec.-butylurea -1 25 Long chain fattyalcohol sulfate (emulsifying agent) 2 Goulac (dispersing agent) 3Kerosene 70 3- 2-chloro-4-ethylphenyl) -1-diethylurea 30 Alkylated arylpolyether alcohol (wetting and emulsifying agent) 3 Methyl cellulose(dispersing agent) 1 Kerosene 66 EXAMPLE8 The compositions of thisinvention are oncetive herbicides when applied to foliage. For example,3 (2,4,5 trichlorophenyl) -1,1-dimethylurea was formulated to give acomposition containing by weight of that compound, 18% by weight ofpowdered solid diluent and 2% by weight of wetting and dispersingagents. This formulation was dispersed in water to give aqueous spraycompositions containing various concentrations of the active compound.Each aqueous dispersion was sprayed on three month old quack grassplants from root cuttings to the runoff point. An aqueous dispersioncontaining 0.5% of the 3-(2,4.5-trichlorophenyl)-1,1-dimethylurea wassuflicient to eifect kill of the quack grass in three months. i

I claim:

1. A method for killing weeds which comprises applying to the weeds. inamount sufflcient to exert a herbicidal action, a 3-(o-substitutedphlfinyl) -1,1-dialkylurea represented by the form a:

H o /R' i i t N I R where R is an alkyl radical having up to two carbonatoms, R" is an alkyl radical up to four carbon atoms when R is methyland up to two ca'i'bon atoms when R is ethyl, and A is anorthosubstituted phenyl group selected from the group consisting of m Q-Q' .Q

where R is an alkyl radical having up to two carbon atoms, R is an alkylradical up to four carbon atoms when R is methyl and up to two carbonatoms when R is ethyl, and A is an orthosubstituted phenyl groupselected from the group consisting of 'where X is halogen, n is apositive integer up to 2, and R is alkyl having up to four carbon atoms,the ortho-substituted phenyl group having one hydrogen on one of thenuclear carbons ortho to the group NHCON(R')R". I

9 3. A herbicidally active 3-(o-substituted phenyi)-1.1-dialkylurearepresented by the formula where X is halogen, n is a positive integerup to 2, and R. is alkyl having up to four carbon atoms, theortho-substituted phenyl group having one hydrogen on one 01' thenuclear carbons ortho to the group --NHCON(R')R".

CHARLES W. TODD.

References Cited in the tile of this patent UNITED STATES PATENTS NumberName Date 2,029,959 Urbain Feb. 4, 1936 2,210,442 Balle et a1. Aug. 6,1940 2,280,756 Sankaitis Apr. 21. 1942 2,322,761 Lontz June 29, 19432,341,868 Hitchcock et a1 Feb. 15, 1944 2,374,485 Haury Q. Apr. 24, 19452,412,510 Jones Dec. 10, 1946 2,472,347 Sexton June 7, 1949 FOREIGNPATENTS Number Country Date 574,995 Great Britain Jan. 30. 1946 OTHERREFERENCES Thompson et al., Botanical Gazette." vol. 107 (1949) pp. 494and 498.

Hunter, "J. Chem. Soc, (London), 1927, pp. 1209 to 1213.

3. A HERBICIDALLY ACTIVE 3-(O-SUBSTITUTED PHENYL)-1,1-DIALKYLUREAREPRESENTED BY THE FORMULA